Several years ago studies were conducted among former American prisoners of war to determine what methods used by the enemy had been most effective in breaking their spirit. The findings revealed that they did not break down from physical deprivation and torture as quickly as they did from solitary confinement or from disrupted friendships caused by frequent changing of personnel. Attempts to get the prisoners divided in their attitudes toward one another proved to be the most successful method of discouraging them. It was further learned that the soldiers were not sustained primarily by faith in their country or by the rightness of the cause for which they fought. They drew their greatest strength from the close attachments they had formed to the small military units to which they belonged.
These observations help us understand why Christians need the group experience of fellowship with other believers to help them sustain the new life in Christ.
[from a sermon by Jim Davis: http://www.focusongod.com/Acts04s.htm]